The present invention generally relates to digital rights management and, more particularly, to a backup of digital rights.
Digital rights management (DRM) describes a concept by which media providers enforce limitations on usage and distribution of digital media content. Presently, there are number of DRM schemes in use. For example, mobile content providers use the Open Mobile Alliance (OMA) DRM system to protect digital mobile media content.
The OMA DRM family comprises digital rights management standards that are developed by the Open Mobile Alliance. To date, the OMA DRM family comprises:                OMA Digital Rights Management 1.0 (DRM v1.0),        OMA Digital Rights Management 2.0 (DRM v2.0),        OMA Digital Rights Management 2.1 (DRM v2.1),        OMA DRM v2.0 Extensions for Broadcast Support (XBS),        OMA Secure Removable Media (SRM),        OMA Secure Content Exchange (SCE).        
The OMA DRM system enables content issuers to distribute DRM protected content and rights issuers (RIs) to issue rights objects (ROs) for the DRM protected content. The DRM system is independent of media object formats, operating systems, and run-time environments. Contents protected by DRM can be of a wide variety, including games, ring tones, photos, music clips, video clips, streaming media, etc. For a user consumption of the content, users acquire permission to DRM protected content by contacting rights issuers, i.e. an entity that issues rights objects to DRM conformant devices. Rights issuers grant appropriate permission for the DRM protected content to use it on DRM conformant devices. The content is cryptographically protected when distributed and, hence, will not be usable without an associated rights object (RO) issued for the users device.
DRM protected content can be delivered to the device by any means, for example, over the air, LAN/WLAN, local connectivity, removable media, etc. Rights objects, however, are tightly controlled and distributed by the rights issuer in a controlled manner. DRM protected content and rights objects may be delivered to the device together or separately.
Within the scope of the OMA DRM family, there is a fundamental difference between a backup of rights and a move of rights between devices.
The backup of rights comprises copying an OMA DRM v2.x rights object (RO) from a originating device to another medium or a backup-device. The copied rights object is called backup rights object. However, the backup rights object remains cryptographically bound to the originating device, such that it can only be restored or reinstalled to the originating device. A backup rights object cannot be used to exercise the rights on any other device than the originating device.
The backup of rights is possible from OMA DRM v2.0 onwards. The process of restoring or reinstalling a backup rights object and making it usable on the device is called installing a backup rights object.
Currently, backup-device storage of licenses or rights objects is limited to a plain backup function. The backup is seen as a “proprietary” function of the originating device to which the license or rights object is bound. The backup format is typically implementation (vendor) specific.
As an example, the OMA DRM standards specify that rights objects may be backed up but there is no common format, in which DRM rights objects are stored. The lack of specification of the format, results in proprietary backup formats for every vendor specific implementation. There is no provision to use the backed up ROs for other purposes than the backup function.
Currently, the OMA DRM standards where backup is foreseen are:                OMA Digital Rights Management 2.0 (DRM v2.0),        OMA Digital Rights Management 2.1 (DRM v2.1),        OMA DRM v2.0 Extensions for Broadcast Support (XBS),        OMA Secure Removable Media (SRM),        OMA Secure Content Exchange (SCE).        
OMA DRM v2.1, XBS, SRM and SCE are all based on OMA DRM v2.0. In the OMA DRM v2.0 specification, it is described that a rights object may leave the originating device, provided that it leaves “in a protected form”. What this protected form exactly is, is not specified and depends on the implementation.
If the format of backed up rights objects is not specified, they can only be treated as “black boxes” on an external storage. By looking at a black box rights object, it is not possible                to associate the license to the originating device,        to associate the license to a specific media content,        to evaluate rights offered by the rights object,        to see who issued the rights object.        
This makes it difficult for a user to keep track of the rights objects that the user has acquired for his devices. Even if the user backs up all his rights objects to a central off line storage, the user has no way to use this for an overview of his rights objects (and the remaining rights). If a users rights objects were acquired using more than one device, the user may have a difficult time to get a good overview of all his rights objects by looking at the individual devices. This situation is aggravated if part of his devices are portable devices with limited user interface options. Further, it may be difficult to restore the backed-up rights objects to the proper device. The user needs to “manually” keep track of an association between rights object and its originating device.
Vendor specific rights objects implementations make it difficult to write general tools for backup administration or management.
It may also be a problem that vendor specific implementations of the backup format may differ in security.
In addition there are specific problems for the OMA DRM family. One possibility to perform a “state of the art” backup of a OMA DRM rights object in a protected form, is by storing it in its original form on an off-device storage. However, this has the drawback that when such a rights object is restored to the originating device, it cannot be distinguished from an out-of-band delivered rights object, i.e. a rights object, which is not delivered via the rights object acquisition protocol (ROAP). Since restrictions apply for accepting out-of-band delivered rights objects, not all backed-up rights objects can be restored. For example, out-of-band delivered rights objects may be signed by the rights issuer, therefore non-signed rights objects may not be restored to the originating device from a backup device. If no special backup format is used and rights objects are backed-up by storing them unmodified on external storage, only signed rights objects can be restored.